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  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
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  <script>
    let [a, b, c, d] = [1, 2, 3];
    console.log(a);	// 结果为：1
    console.log(b);	// 结果为：2
    console.log(c);	// 结果为：3
    console.log(d);	// 结果为：undefined
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